APHASIA

Aphasia is a disorder that results from damage to portions of the brain that are responsible for language. For most people, these areas are on the left side of the brain. Aphasia usually occurs suddenly, often following a stroke or head injury, but it may also develop slowly, as the result of a brain tumor or a progressive neurological disease. The disorder impairs the expression and understanding of language as well as reading and writing. Aphasia may co-occur with speech disorders, such as dysarthria or apraxia of speech, which also result from brain damage.

Causes of aphasia

Aphasia is caused by damage to one or more of the language areas of the brain. Most often, the cause of the brain injury is a stroke. A stroke occurs when a blood clot or a leaking or burst vessel cuts off blood flow to part of the brain. Brain cells die when they do not receive their normal supply of blood, which carries oxygen and important nutrients. Other causes of brain injury are severe blows to the head, brain tumors, gunshot wounds, brain infections, and progressive neurological disorders, such as Alzheimer's disease.

Types of Aphasia

Global aphasia

This is the most severe form of aphasia, and is applied to patients who can produce few recognizable words and understand little or no spoken language. Persons with Global Aphasia can neither read nor write. Global aphasia may often be seen immediately after the patient has suffered a stroke and it may rapidly improve if the damage has not been too extensive. However, with greater brain damage, severe and lasting disability may result.

Broca’s aphasia (non-fluent aphasia)

In this form of aphasia, speech output is severely reduced and is limited mainly to short utterances of less than four words. Vocabulary access is limited and the formation of sounds by persons with Broca's aphasia is often laborious and clumsy. The person may understand speech relatively well and be able to read, but be limited in writing. Broca's aphasia is often referred to as a 'non fluent aphasia' because of the halting and effortful quality of speech.

Mixed non fluent aphasia

This term is applied to patients who have sparse and effortful speech, resembling severe Broca's aphasia. However, unlike persons with Broca's aphasia, they remain limited in their comprehension of speech and do not read or write beyond an elementary level.

Wernicke’s aphasia (fluent aphasia)

In this form of aphasia the ability to grasp the meaning of spoken words is chiefly impaired, while the ease of producing connected speech is not much affected. Therefore Wernicke's aphasia is referred to as a 'fluent aphasia.' However, speech is far from normal. Sentences do not hang together and irrelevant words intrude-sometimes to the point of jargon, in severe cases. Reading and writing are often severely impaired.

Anomic aphasia

This term is applied to persons who are left with a persistent inability to supply the words for the very things they want to talk about-particularly the significant nouns and verbs. As a result their speech, while fluent in grammatical form and output is full of vague circumlocutions and expressions of frustration. They understand speech well, and in most cases, read adequately. Difficulty finding words is as evident in writing as in speech.

Other forms of aphasia

• Transcortical motor aphasia: This is similar to Broca's aphasia but usually not as severe. A key difference is that people with this don't have a problem repeating back phrases or sentences you say to them.
• Transcortical sensory aphasia: This type is similar to Wernicke's aphasia but usually not as severe. Like with transcortical motor aphasia above, people with this type don't have a problem repeating back what you say. This type of aphasia is common with degenerative brain conditions like Alzheimer’s disease.
• Conduction aphasia: This type of aphasia affects fluency but not understanding. People with this struggle to pronounce words, especially when trying to repeat something you say to them.
• Mixed transcortical aphasia: This aphasia is like global aphasia, except that people with this can still repeat what people say to them.
• Anomic aphasia: People with this kind of aphasia struggle to find words, especially names of objects or words that describe actions. To get around this problem, they often use several words to explain what they mean or non-specific words like "thing" instead.

Other conditions that involve or look like aphasia

• Progressive primary aphasia (PPA). Though it has “aphasia” in the name, this is actually a degenerative brain disorder. People with this condition gradually lose the ability to speak, write, read or understand what others are saying. This is different from injury- or stroke-related aphasia, which doesn’t get worse over time. Different forms of PPA happen with diseases like frontotemporal dementia and Alzheimer’s disease.
• Alexia (word blindness) and agraphia (inability to write). Damage to the parts of your brain that control your ability to speak can also affect your reading and writing abilities. People with alexia can see words but can't recognize or read them. People with agraphia lose the ability to write. These can happen at the same time, but in rare cases, people can have alexia without agraphia, meaning they can write words but then can't read what they wrote.
• Auditory verbal agnosia. This is a condition where a person can hear people speaking but can't recognize that what they hear is other people talking. It happens when there's a disruption in an area of the brain that processes sound or spoken language.

Category	Type	Symptoms
Nonfluent	Broca’s aphasia	You know what you want to say and can understand others. However, speech is difficult and requires great effort. Short phrases are often used, such as “Want food.” Some weakness or paralysis of the limbs on one side of the body may also be present.
Nonfluent	global aphasia	This is the most severe aphasia. You can’t produce and sometimes can’t understand language. However, you’ll still have normal cognitive ability in areas not related to language and communication.
Nonfluent	transcortical motor aphasia	You can understand language but can’t communicate fluently. You may use short phrases, have a delay in response time, and frequently repeat things.
Fluent	Wernicke’s aphasia	You can speak in long sentences. However, these sentences have no obvious meaning and can contain unnecessary or even made up words. Trouble with understanding language and with repeating things is also present.
Fluent	conduction aphasia	You can still speak fluently and can understand language but have trouble with repetition and finding words.
Fluent	anomic aphasia	This is a more mild aphasia. Your speech is fluent and you can understand others. However, you’ll often use vague or filler words. You may often feel like a word is on the tip of your tongue and may use other words to help describe the word you’re looking for.
Fluent	transcortical sensory aphasia	You have trouble comprehending language, although you can communicate fluently. Like Wernicke’s aphasia, your sentences may have no obvious meaning. But unlike Wernicke’s aphasia, you’re able to repeat things, although echolalia may occur in some cases.

Causes

Aphasia can happen with any condition that damages the brain. It can also happen with problems that disrupt your brain’s functions. Possible causes for this include:

• Alzheimer’s disease.
• Aneurysms.
• Brain surgery.
• Brain tumors (including cancer).
• Cerebral hypoxia (brain damage from lack of oxygen).
• Concussion and traumatic brain injury.
• Dementia and frontotemporal dementia.
• Developmental disorders and congenital problems (conditions that you have when you’re born because of a problem while you developed in the womb)
• Epilepsy or seizures (especially if these cause permanent brain damage).
• Genetic disorders (conditions you have at birth that you inherited from one or both parents, such as Wilson’s disease).
• Inflammation of your brain (encephalitis) from viral or bacterial infections, or autoimmune conditions).
• Migraines (this effect is temporary).
• Radiation therapy or chemotherapy.
• Toxins and poisons (such as carbon monoxide poisoning or heavy metal poisoning).
• Strokes or transient ischemic attacks (TIAs).